Condensing, Ultra-Low NOx Gas-Fired Humidifier
A gas-fired atmospheric pressure steam humidifier having high efficiency and ultra-low NOx(3) emissions is disclosed. In some examples, the gas-fired humidifier can have an efficiency of greater than 90 percent and a NOx(3) output of less than 20 parts per million (ppm). In one aspect, the humidifier includes a secondary heat exchanger having a first heat exchange section for pre-heating combustion air and a separate second heat exchange section for pre-heating make-up water, wherein the first and second heat exchange sections are in heat transfer communication with exhaust gases generated by the gas-fired burner and combustion blower assembly. In some examples, the first heat exchange section includes orifices for enabling flue gas recirculation.
1 . A gas-fired humidifier comprising:
a. an atmospheric pressure storage tank for holding a volume of water, the storage tank having a make-up water inlet and a steam outlet;
b. a gas-fired burner and combustion blower assembly;
c. a primary heat exchanger connected to the gas-fired burner and combustion blower assembly, the primary heat exchanger being located within the atmospheric pressure storage tank and configured to heat the volume of water to generate steam;
d. a first heat exchange section for heating a first fluid stream; and
e. a second heat exchange section for heating a second fluid stream;
f. wherein the first and second heat exchange sections are in heat transfer communication with exhaust gases generated by the gas-fired burner and combustion blower assembly.
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